Just the arm.

[His ribs are killing him but while he does not, actually, get off of in it, the pain is a relief, in many ways.]

Look, I know what internal injuries feel like. If anything serious were wrong I'd have gone to the infirmary.

[Probably. And now he carefully, awkwardly pushes himself up into a handstand. The fact he doesn't even try doing push-ups like that, just concentrates on staying upright, is possibly telling.]